Dresden 2003 – wissenschaftliches Programm

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M: Metallphysik

M 25: Flüssige und amorphe Metalle II

M 25.2: Vortrag

Dienstag, 25. März 2003, 12:00–12:15, IFW D

Mechanical Properties and Thermal Stability of Cu-based Bulk Metallic Glasses and Nano-Composites — •Mariana Calin^1,2, Jürgen Eckert¹, and Ludwig Schultz¹ — ¹IFW Dresden, Institute for Metallic Materials, P.O. Box 270016, D-01171 Dresden, Germany — ²University ”Politechnica” of Bucharest, Materials Science and Engineering Faculty, Bucharest, Romania

Cu₄₇Ti₃₄Zr₁₁Ni₈ and Cu₄₇Ti₃₃Zr₁₁Ni₈X₁ (X = Fe, Mn, Sn, Si) 2 mm thick bulk glassy rods were synthesized and characterized by X-ray diffraction, differential scanning calorimetry (DSC), transmission electron microscopy and compression tests. The DSC studies reveal the beneficial role of small addition of the X elements on the thermal stability of the glasses. Large supercooled regions (ΔT = 47 ÷ 57 K) and good thermal stabilities (T_x = 743 ÷ 760 K) are recorded. The alloys possess good mechanical properties under compressive loading at room temperature, i.e. Young’s modulus of 100 ÷ 109 GPa, yield strength of 1881 ÷ 2102 MPa, fracture strength of 2040 ÷ 2186 MPa and elastic strain of 2.1 ÷ 2.4 %. Significant plastic strain (2.2 %) was only found for the Si-containing glassy alloy, which exhibits a unique nano-composite microstructure consisting of Cu-rich nanocrystals homogeneously dispersed in the glassy matrix. The improved ductility can be explained by the formation of multiple shear bands rendering the alloy resistant to crack propagation.